Skype.com claims over 90 million downloads of its VOIP software. It was started by the same guys who started Kahzza(?SP) PtoP file sharing. I've been using it to make calls to NewYork, Switzerland & Latvia with very satisfactory results & major savings. I started using it once I read GTEL was chasing this business vector. VOIP has the potential to erase the lock TELCOs have on the business market. Skype to Skype calls are free. The evolution of VOIP will ride the Super Hub Network.
(The last one is the old message board of ITXC, which was taken over by iBasis posters when the company was swallowed up by Teleglobe - almost an anagram of GlobeTel. Coincidence or more?)